Polyrotaxanes including a cyclic molecule, a linear molecule threading through a cavity of the cyclic molecule in a skewered manner, and capping groups capping both ends of the linear molecule are expected to have applications in various fields because of their specific viscoelastic characteristics. Use of polyrotaxanes as crosslinking agents is considered in order to impart their specific viscoelastic characteristics to materials.
As a material in which a polyrotaxane is used as a crosslinking agent, Patent Literature 1 discloses a urethane elastomer with a small permanent strain, low stress relaxation properties, and a low hysteresis loss.
Patent Literature 2 discloses a pressure-sensitive adhesive having both high stress relaxation properties and a high holding power which are achieved by crosslinking a (meth) acrylic acid ester copolymer having a hydroxy group with a polyrotaxane.